Two Ways to Spread Light
by geoclaire
Summary: "There are two ways to spread light: to be the candle, or to be the mirror that reflects it". Sarah and Delphine renegotiate boundaries once Cosima starts getting better. Part three of "Better to light a candle than to curse the darkness".
1. Chapter 1

Sarah doesn't look at Cosima like a sister.

In a way, it takes her weeks - _weeks_ \- after she returns from Frankfurt, to see it. It takes that long to see that the way Sarah regards Cosima, the way she ducks her head to her whiskey glass and her cheeks colour so slightly, the way she sways between her feet when Delphine is around. It takes that long to see that her glances, her way of steadying Cosima with her hand on her hip, the way she unconsciously admires the low cut of Cosima's overly gauzy tank tops, are not sisterly.

In another way, it took only seconds of being in the room with them both for the skin on the back of her neck to rise. It took only Sarah's quick look, as Cosima flung herself joyfully into Delphine's arms, for some repressed animal instinct of hers to come burning to life and identify Sarah as a competitor, a threat to her and hers.

Inevitably, reality cuts through. It takes a month, but it happens like this: she drops Cosima off to help Sarah understand her research about the differing health issues integrated into the Castor clones. Sarah is staying at Mrs S' house with Kira, and Delphine helps Cosima's slender form up the snow covered path, teasing and jostling as they go. She's gentle against Cosima's stark hips, but Cos is grinning, enthused at the prospect of science and from half a cone of weed with her breakfast. They slide past Sarah, still in the doorway with her hands around her Earl Grey, and she deposits Cosima onto the couch as a loose bundle of free falling, happy limbs.

Delphine tucks Cosima onto the couch, and they kiss, and then her phone is buzzing as she's standing, and she's always been inclined to wander when she speaks on the phone, so she's in the kitchen when she turns and sees Sarah slide onto the couch by Cosima and lightly raise her face with two fingers under her left jawbone.

Delphine stops listening to her phone call.

Cosima lifts her face to Sarah's, and their eyes meet, and Cosima's hand is on Sarah's arm now and their gaze doesn't break. Sarah leans in a little, saying something soft that Delphine doesn't catch, and Cosima twitches her head to the side and then tucks it closely below Sarah's jaw instead.

Sarah's shoulders drop with the longest exhale she's seen her give. Sarah Manning breathes from her chest, doesn't let anything get deep inside her. She exhales, and slides her arm around Cosima.

"Delphine? Hey, Delphine? I think you're dropping out, can you hear me?"

She flinches. " _Qui._ Yes, I'm sorry, I can hear you now. Please tell me again about the trial results?"

She knows now why she'd felt that sudden, brutal shot of adrenaline.

* * *

She goes to work. She spends the day in a preoccupied daze and if the Dyad continued to hire her for anything more than theoretical access to one of the clones, she'd fear for her job security.

How long had she missed this? How long had this been going on? Was there, in fact, anything happening? Perhaps she'd misread their interaction. Perhaps she was panicking, pointlessly, over nothing more than a close and affectionate bond. They hadn't kissed, after all, no matter what she thought she'd begun to see.

She hopes for this. Wants it. But she turns over their interaction in her head - Sarah's hands, tender on Cosima's face, the way Cosima had turned her head into the touch - and _knows_ , deep in the pit of her stomach.

Sarah has touched Cosima. Has in all likelihood fucked her, put her hands and her mouth where Delphine has done all too infrequently. Sarah has seen the way tension builds up in Cosima's stomach, caused the crease that forms between her eyebrows when she's close, heard the way Cosima laughs in bed. It guts her.

Delphine had taken her to bed only last night, gone down on Cosima for ages before being flipped and pressed improbably hard into the mattress. Cosima had been exhausted afterwards, slept unmoving on her side right through the night, but she'd never once paused in her actions or her enthusiasm. Delphine hadn't thought to doubt that Cosima wanted her, loved her still. She'd said it, during, and slurred it again as her eyes closed, glasses pressing awkwardly into her cheek.

Delphine stays at her desk and works uselessly, mechanically. She files and tests and answers emails, rereads research on speculative stem cell technology. She even finds it in her to smile briefly, when Cosima texts her bad puns around lunchtime. But she doesn't reply, and she stays at her desk and works. She works well past when she'd agreed to pick Cosima up.

She doesn't reply to the texts that gradually, then increasingly, collect on her phone. Once six passes, she stops reading them, doesn't answer, either, the repeated calls.

At some point, she realizes she's been sitting motionless, head in her hands, for longer than she can remember. Her back aches when she finally straightens, dragging her hands, wincing, through her hair. She needs painkillers, or a drink, and one is absolutely not going to be enough.

And she looks up, and Sarah is there. Still in a way that Cosima could never manage, watching her.

Delphine drops her hands, straightens her back, but doesn't stand. She'll fight, but not with fists. Not like Sarah does.

"How long?" she asks coldly, " How long have you been fucking her?"

Cosima is all movement, but Sarah is taut. She stares, then ducks her head, and there's something so Cosima in it that Delphine aches. Goddamnit, they're clones for christ's sake, how can they be identical and so unalike? Sarah shifts her weight, her leather jacket brushing the door frame, and shrugs a little.

"It ain't like that between us," is her answer, and Delphine could scream at the lie.

"No?" she's glacial, the words a twisting knot in her throat. " You haven't fucked her?"

Sarah exhales hard through her nose, raking her hand through her hair now. "No. Not since you've been back," she says.

That wasn't what she'd expected to hear. It makes her pause, and perhaps it assuages some of the hurt born from thinking Cosima would fuck her and then go to Sarah for the same. Some. But did it matter?

"Besides," Sarah says, begrudgingly, "it ain't like that." She's looking down, seeming to grope for words, looking for a concept that's as hard to say as to feel. "It ain't about the sex. I mean, it is, but like - not just that."

She looks up, catches Delphine's gaze. Her eyes are shining. Maybe she believes her, or maybe it's just masochism, but Delphine hears herself asking, "Well then what is it _like?"_

For the first time, Sarah leaves the doorway. Her ever present boots make a soft tread, but her proximity seems sudden when she slips her fingers lightly along the edge of Delphine's desk. Her gaze is detached, almost impersonal, as she looks over the lab, computer screens still on and microscopes still loaded with samples, the fridges laden.

"I wanted her to live," she says abruptly. "That's all, to begin with. I want her to live, and she's," she makes a frustrated gesture, "all stuck in her head, Cos, and I - _we_ \- we need her."

 _I need her_ , Delphine understands. But _I need her too_ screams inside her.

Sarah's closer now, and how is it that she's both taller and skinnier than Cosima? It makes no biological sense. _Genotype and phenotype, environmental influences_ , supplies her brain, but Sarah's saying, "It wasn't her idea, if that helps." She stops, considering, and snorts, "Not my idea, exactly, either, but she - she didn't start anything."

Delphine stares at her, then her hands. It would be easy to blame Sarah. She's making it easy, even, and it helps a little to think that Cosima wasn't the first to look at her clone and think _what if_. It helps to think Cosima didn't wait for her to leave the country only to fall into bed with Sarah Manning, Rachel's _unmonitored tramp_. And perhaps it would help if she could look at Sarah and see someone who took advantage of Cosima, someone who wrangled caring for an invalid into getting into her bed. But that isn't what this feels like.

Before, she'd tried not to let her imagination get involved, but her renegade brain had still spat up writhing images of the two of them together, limbs entwined and skin flushed, Cosima's moans underlined by Sarah's low cursing. Now, the picture she draws is more innocent, somehow chaste, of an ill Cosima and despairing Sarah.

She exhales, impatient. It doesn't sound as though Sarah had arrived, seen an opportunity, and started something in a lustful haze. It sounds as though Cosima was dying, and Sarah was desperate, and used every tool in her arsenal. But Sarah doesn't fight with her words. Logic, and science, and coolly thought out rationales, that's all Delphine's territory.

Delphine wants Cosima to live, too.

She stares again at Sarah, in her boots and leather jacket and her tight jeans. The eyeliner that has recently reappeared under Cosima's tutelage. The tousled hair, the flannel. She can see the appeal, even forgetting that her face is Cosima's.

Sarah's studying her too now, still closer, and Delphine can feel her gaze like the sun. Perhaps that's what drew Cosima to her, too.

Sarah extends her hand, but doesn't touch her. "She wants you to come home, Delphine. Really," and she pauses, "You need to talk to Cosima."


	2. Chapter 2

Sarah drives her home in a beaten up pickup that has seen better days.

Home, Delphine realises halfway, isn't her own home, but Mrs S' place where she'd brought Cosima to Sarah that morning. Sarah parks out the front, and gets out, but Delphine stops. She looks up at the house windows, seeing the hint of a figure moving behind a curtain, and has to close her eyes before she can leave the car.

Sarah's waiting for her on the verge. "Don't lose it now," she warns, and Delphine nods, pulling her jacket more tightly around her. Sarah studies her, then turns on her heel and heads into the house. She follows, hovering behind as Sarah unlocks the door and ushers her in.

She stands at the base of the steps, taking her coat off, and then there's a shuffling noise and Cosima emerges into view in the living room. And despite everything, something goes light in her chest just at the sight of her, a unique giddiness rearing to life.

She's draped softly in one of the many throw blankets Mrs S keeps about the house, and the doctor in Delphine hums with approval. Cosima is unlikely to relapse at this point, but she's better off protecting her immune system at every turn. She scans up, and catches Cosima's eyes. Maybe it's in her head, but they seem darker than she's used to.

Sarah clears her throat behind her, and Delphine breaks their gaze, turning to look at her. Sarah's standing on the bottom-most step, toying with the zipper tag on her leather jacket. "I'm gonna…" she says, and gestures upstairs.

Delphine nods brusquely, and turns back in time to see the flash of Cosima's glasses as her gaze trails Sarah up the stairs.

She looks tired, and despite herself, she takes Cosima's arm and guides her back into the living room. She sees it when Cosima looks at the couch under the window, then resolutely selects one of the armchairs instead. She can't bring herself to sit, leans against another chair instead. She doesn't know how to start.

"Were you ever going to tell me?" she asks.

Cosima shifts a little, resettling the blanket around her. "I hadn't decided," she answers after a moment, rubbing the fabric between her fingers. "Does it matter?"

"I - _of course_ it matters, Cosima!" She's shocked at the implication, although perhaps not as much as she'd have been an hour ago. Sarah hadn't explained, exactly, but she'd shared enough to have Delphine questioning her assumptions.

"Okay, yeah," She concedes, looking at her hands, "Yeah, it matters. But Del, I…" she looks up at Delphine now, and she feels her own height in that gaze. "I didn't know if you were coming back. Not really."

She's stung. "I was coming back!" she responds immediately, then softens. Cosima hadn't known that, not for sure. "Cosima, _cherie_ , of course I was coming back. I would always have come back to you."

Cosima shrugs a little, uncharacteristically unsure, and her heart hurts to think of Cosima sick, Cosima doubting, Cosima not sure she would be alive to see Delphine return. They hadn't even spoken when she'd been so hurriedly sent away, and it had been weeks before she'd found a way to get back in contact. Weeks in which she was afraid Cosima might already have died, struck down so much faster than Jennifer by the full force of the clone cancer.

Of course Cosima had been unsure. Of course she'd been afraid, and alone, and needed comfort and contact from the people still around her.

Cosima tips her head to the side, shrugging her cheek to her shoulder, "I know that, now. But not then, not totally for sure. And…" she's uncomfortable now, "It's not like we talked about monogamy or anything."

That prickles at her, the injustice of it, but it's not something she can fight. They'd never talked about monogamy because they'd never had time to talk about a lot of things. And if she begrudges Cosima this… she has her own glasshouse, one of betrayal and monitoring and Leekie. If she starts throwing stones, it's sure to fall in. And it's not the point.

"I know," she says eventually. She doesn't know how to follow it that.

"Do you…" Cosima's struggling, and she turns her hands up in appeal. "Is there anything you want to know?"

Delphine watches her hands, her broad gestures. Sometimes, she thinks she trusts them more than anything that comes out Cosima's mouth: Cosima can't lie with her hands. When Sarah had mimicked her, it had been the first thing that tipped her off. "Have you been together since I came back?"

"No." It's instant.

Good. Sarah hadn't lied. They'd omitted, clearly, but so far she didn't have reason to believe anyone had actively lied to her. That made a difference.

"How did it start?"

Startled, Cosima looks up, studies Delphine's face. "Are you sure?" she asks.

Delphine doesn't pretend not to understand. "I need to know," she says gently, and Cosima looks at her a moment longer before she nods.

"Sarah... She stayed with me, after... After you left." She fiddles with the blanket again, running the woollen tassels between her fingers. "I mean, everyone did, in shifts and that, but... She had a hell of a lot on her plate, with Kira, and Helena going missing - did you know about that? She up and disappeared one night, and it took us a hell of a long time to figure out it wasn't even her going off on her own but more clone bullshit..." She shrugs, "Not the point, but Sarah was hella busy, more than anyone, but she kept coming back,and eventually it started meaning something.

"She stayed with me even when things looked really hairy, like, coughing and choking in the night, a bunch of seizures... Sorry," she adds, responding to the look Delphine knows is on her face, "but like, she stayed, and she wasn't scared of me like Alison was, and we used to share the bed and when I was totally out of it, she'd hold me.

"And I freaked out a bunch, about you and about DYAD and about like, maybe, probably, dying, and she'd listen, and she tried to help. And then one day I was just super ill, and totally upset thinking I was going to die soon, and just feeling like nothing good was ever going to happen to me again, and she kept looking at me, and I got halfway through some incoherent rant and she was holding me and... Kissing my face... And then kissing me."

Cosima finally looks up at her, and Delphine knows her face must show the thoughts rushing through her head. Before, Cosima hadn't wanted to talk about how ill she'd been. Delphine knew, of course, could work it out, but Cosima hadn't ever wanted to talk about it. And she had to wonder, with Cosima so unwell...

"Cosima... It was consensual, yes?"

Her head comes up, dismayed, and her answer is rushed, "Yeah. Uh, yeah, Delphine, don't go thinking, like, I appreciate the concern, but I wasn't, um, I wasn't so sick I didn't know what I was doing," she finishes, somehow urgent and gentle at once, "I just... Didn't think I had a reason not to, you know? I didn't think it was going to matter."

She can read between those lines, doesn't care to.

"And then you kept going." It isn't a question.

Cosima scratches her head, toys with a loose dreadlock. " Yeah. Like, why not, I guess, on my side, and Sarah..." she gestures loosely, "I dunno, it was like... Like it was her way of bribing me, I guess. To keep getting better." She stops, thinks, "But... More than that, I think? It was like it was the only way she knew how to fight for me. Like, she couldn't rebuild my lungs, but she could make me feel enough good things to want to keep fighting," Delphine twitches, "Sorry, um, overshare," she adds awkwardly.

It hurts, Delphine's big enough to admit that. But it hurts more, perhaps, to hear Cosima talk so plainly of having reached a point where she implies clearly that she'd given up. If Sarah had given her a way to get past that, to find the will to live...

It had never been a betrayal, not really. Not exactly. More a statement of need, and uncertainty, and insecurity. Desire, perhaps, but not in the first instance, but secondary to the need for connection and life. And it must be the strongest of feelings to know Sarah Manning is on your side.

" She fought for you," Delphine muses, and Cosima blinks, answers it like a question.

" Yeah. Uh, yeah, I guess so."

"I fought for you, too," Delphine reminds her, and Cosima's face darkens. "Ah, no, cherie, I do not mean it like that. I mean," and for the first time she comes closer balancing on the edge of Cosima's chair to touch her face, her hair. She traces Cosima's ear with a fingertip, the arm of her glasses, the arc of her eyebrow. Cosima tilts her head up to her, closing her eyes and leaning into the touch, and she's luminous in her loveliness. Delphine smiles, "I mean that I love you," and she kisses her.

It takes Cosima a moment to respond, her mouth slightly open but still, and Delphine takes advantage, slips her tongue past her teeth in an instant. She teases her tongue with her own, and that's when Cosima responds, her lips a little dry but familiar and so, so good.

She'd worried that, knowing, it would be different. That somehow Cosima would be different, taste different, move differently. But Cosima moans softly beneath her, teeth tugging at her lower lip, and it is different, but it's good. Cosima is still soft, gently urgent, pliant but engaged beneath her lips. And now, finally, she knows everything.

"And to think I was worried she'd killed you," Sarah drawls, and Delphine twitches upright before she remembers not to. "Chill, Delphine, I just was expecting more shouting."

She draws away from Cosima, who's already regained her composure, her eyebrows raised. "Since when do you say 'chill'?" she asks Sarah incredulously. "You are like the least chill person I know."

Sarah rolls her eyes, catching Delphine's accidentally, and she flushes a little but then seems to decide not to. "You've never seen Fe trying to choose clothes to club in, then," she says, but it lacks her usual swagger and falls flat.

Cosima laughs awkwardly, and Delphine's staring at the ground now. She's never been quite comfortable around Cosima's sisters, and now she doesn't know what to do. There's a beat, then Cosima's getting up, "Come here," she says, and Delphine and Sarah both come forward to support her before she's even specified.

Cosima puts her hand on Delphine's wrist, stabilising, then holds her other arm to Sarah. She comes to her without a query, and Cosima wraps her free arm around her, still holding onto Delphine. "It's okay," she says softly to Sarah, and Sarah closes her eyes where she's tucked her head against Cosima's shoulder, relaxing into her. "It's going to be okay."

With Cosima, Sarah becomes soft. It's that softness, she thinks, that had Sarah come to her earlier, had explained in a way so that Delphine could understand.

She turns her hand over beneath Cosima's fingers, holds them in her own. "It's going to be okay," she echoes, slipping her arm around Cosima, and ducking down to kiss Sarah's shining hair.


End file.
